User-side Techniques
- IMPETUS Consortium
User-side techniques mainly aims at empowering the data owner, for instance through the implementation of user-centric data management systems.
The user-centric data management model is introduced to automate and support users' identity management at the user side. Users are given the control over their identities, i.e., considered as a collection of attributes, and they are able to select information to disclose and to be notified when their information are collected. Users' consent is also required for any type of analysis and manipulation over their collected information. The user identity and attributes can be stored in a hardware device (e.g., smart card, portable personal device). As such, the user only needs to memorize one credential (i.e., to access to the hardware device) instead of remembering several identifiers and credentials.
Among user-side management implementations, we can mention the OpenID framework that is already used in well-known Web platforms such as Drupal and WordPress. In the OpenID framework, a user can be identified by an URL (Uniform Resource Locator) or an XRI (EXtensible Resource Identifier) address. The uniqueness of URLs, resp. XRIs, makes the user uniquely identified. OpenID enables a user to choose his identity provider as well as his identity.
Various prototypes have been also proposed and considered as fundamental building blocks in privacy user-centric data management systems. Indeed, every data owner can prove to a service provider (data processor), that he holds validated properties, referred to as credentials, obtained from issuing authorities. These techniques permit to prevent service providers to -trace- users’ activities based on successive communication sessions.
User-side methods attract a lot of interest and complete consideration from industries and academia, thanks to their capacity to enforce the data minimization basic component. The design of these systems strongly rely on the use of malleable cryptographic primitives that ensure several interesting properties, such as the selective disclosure feature and the unforgeability property. In fact, the selective disclosure property refers to the ability provided to the user to present to the service provider partial information extracted or derived from his certified information. For instance, to prove he is older than 18 to purchase liquors, while not revealing his birth date. The unforgeability property ensures that unless a user possesses a legitimate and certified credential, i.e., secret key, he is not able to generate a valid authentication proof, i.e., user’s signature over the service provider's access policy.